What to Plant in August — Zone 3

August is the closing stretch of zone 3's season — the average first frost (Sep 20) is only weeks past month's end, so this is fall-sowing and garlic-planting territory.

Fall planting — Counted back from the first fall frost.

🥬 Lettuce Jul 26 – Aug 23 45–60 days to maturity
🍃 Spinach Jul 26 – Aug 9 40–50 days to maturity
🌿 Arugula Aug 9 – Aug 23 30–40 days to maturity
🌶️ Radishes Aug 9 – Aug 23 22–30 days to maturity
🧅 Scallions Jul 26 – Aug 9 60–70 days to maturity
🧄 Garlic Aug 9 – Sep 6 plant cloves; harvest next summer
🥬 Bok Choy Jul 26 – Aug 9 45–55 days to maturity
🌿 Mustard Greens Jul 26 – Aug 9 35–45 days to maturity
🌿 Cilantro Jul 26 – Aug 9 45–55 days to maturity
🌾 Dill Jul 26 – Aug 9 40–55 days to maturity

Windows use zone 3's typical frost dates (May 15 / Sep 20). For your own city's dates, run the frost lookup — the planting calendar then localizes everything automatically.

Frequently asked questions

What can I plant outside in August in zone 3?

10 crops can go in the ground: lettuce, spinach, arugula, radishes, scallions, garlic, bok choy, mustard greens, and 2 more. Exact windows are in the tables above — early and late in the month can differ by a full frost date.

Is August the right time for tomatoes in zone 3?

The spring window has passed; tomatoes set out this late won't beat the Sep 20 average first frost to ripeness. Plan for next spring's seed-starting instead.

August in other zones

Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6Zone 7Zone 8Zone 9Zone 10Zone 11Zone 12Zone 13

Zone 3, month by month

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